Information processing apparatus and program

ABSTRACT

An information processing apparatus is provided that detects brightness and outputs an illuminance value corresponding to the detected brightness, derives a luminance set value for controlling a light emission signal regulating luminance of a light source based on the illuminance value, and displays derived power consumption information related to power consumption of the light source based on the luminance set value.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of and is based upon and claims thebenefit of priority under 35 U.S.C. §120 for U.S. Ser. No. 12/534,627,filed Aug. 3, 2009, and claims the benefit of priority under 35 U.S.C.§119 from Japanese Patent Application No. 2008-231273, filed Sep. 9,2008. The entire contents of which are incorporated herein by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to an information processing apparatus anda program.

2. Description of the Related Art

Various kinds of display apparatus such as an organic EL display(organic ElectroLuminescence display; also called OLED (Organic LightEmitting Diode) display), an FED (Field Emission Display), an LCD(Liquid Crystal Display) and a PDP (Plasma Display Panel) have beendeveloped as alternatives to a CRT display (Cathode Ray Tube display).Among those display apparatus, the liquid crystal display is becomingincreasingly widespread a next generation display apparatus as analternative to a CRT display because of its capability of low powerconsumption driving and reducing costs due to a maturation of productiontechnology, for example. The liquid crystal display is used as a displaydevice that is included in various kinds of information processingapparatus such as portable communication apparatus like a cellular phoneand computers like a notebook PC (Personal Computer), for example. Theliquid crystal display is a non-self-luminous display apparatus thatincludes a liquid crystal panel with a liquid crystal shutter, a lightsource (e.g. a backlight), a polarizing plate for inputting lightemitted from the light source to the liquid crystal panel, and so on,for example.

In such a background, a technique of automatically adjusting luminancein non-self-luminous display apparatus that separately include a lightsource has been developed. A technique of adjusting the luminousintensity of a light source of a liquid crystal display based on adetection result of a photosensor is disclosed in Japanese UnexaminedPatent Publications. Nos. 9-146073 and 4-174819, for example.

SUMMARY OF THE INVENTION

As described above, the liquid crystal display (which is sometimesreferred to hereinafter as “LCD”), which is one kind ofnon-self-luminous display apparatus that separately include a lightsource, is used as a display device that is included in various kinds ofinformation processing apparatus such as a cellular phone and a notebookPC. The information processing apparatus is not limited to be driven byan external power supply, and it may be driven by a finite internalpower supply such as a battery, for example. Thus, some of the aboveinformation processing apparatus include a luminance changeover switchor the like, for example, so as to allow a user of the informationprocessing apparatus to adjust the luminance and the power consumptionof a light source by manual control of the luminance.

However, because human eyes have logarithmic sensitivity characteristicswith respect to outside light, when a user adjusts the luminance usingthe changeover switch, for example, the brightness which the useractually senses and the power consumption of a light source (e.g. abacklight) at that time do not have a linear relationship. It is therebydifficult for a user to estimate the power consumption of a light sourcefrom the brightness of a display device. Consequently, in theinformation processing apparatus having the luminance changeover switchaccording to related art, the following cases (a) and (b) can occur:

(a) Despite adjustment of luminance by a user, the amount of reducingthe power consumption of a light source is not enough, and a batteryruns out during use; and

(b) Despite adjustment of luminance by a user, the luminance is set tobe excessively low due to being overly conscious of the powerconsumption of a light source. As a result, the user keeps using theapparatus while a display screen is hard to read.

An information processing apparatus to which the technique according torelated art that adjusts the luminous intensity of a light source of anLCD based on a detection result of a photosensor (which is referred tohereinafter simply as “related art”) is applied adjusts the luminancebased on a detection result of the photosensor. Further, the informationprocessing apparatus according to related art allows luminanceadjustment by user's manual control. However, in the informationprocessing apparatus according to related art, no measures are takenabout power consumption of the light source. Thus, the informationprocessing apparatus according to related art simply adjusts theluminous intensity of the light source automatically, and a user isunable to keep track of how much power is consumed in the light source.Therefore, the information processing apparatus according to related artdoes not prevent the occurrence of the above-described cases (a) and(b).

In light of the foregoing, it is desirable to provide a novel andimproved information processing apparatus and program that enableadjusting the luminance of a light source based on detected brightnessand presenting a user with information about the power consumption ofthe light source, thereby assisting user's luminance adjustmentoperation.

According to an embodiment of the present invention, there is providedan information processing apparatus that includes an illuminancedetection unit to detect brightness and output an illuminance valuecorresponding to the detected brightness, a luminance control unit toderive a luminance set value for controlling a light emission signalregulating luminance of a light source based on the illuminance value,and a display control unit to derive power consumption informationrelated to power consumption of the light source based on the luminanceset value and display the power consumption information on a displayscreen.

In this configuration, it is possible to adjust the luminance of thelight source based on the detected brightness and present a user withinformation about the power consumption of the light source, therebyassisting user's luminance adjustment operation.

The information processing apparatus may further include a level settingunit to set one luminance level among a plurality of luminance levelsregulating a lower limit and an upper limit of the luminance set value,and the luminance control unit may derive the luminance set value basedon the set luminance level and the illuminance value.

If the set luminance level is changed, the luminance control unit mayderive a luminance set value corresponding to a luminance level afterchange from the luminance set value corresponding to the luminance levelbefore change in a step-by-step manner.

The display control unit may derive at least one of power consumptionand a power consumption rate as the power consumption information.

The information processing apparatus may further include a light source,and a light source control unit to transfer the light emission signalcorresponding to the luminance set value to the light source based onthe derived luminance set value.

The illuminance detection unit may give a notification to the luminancecontrol unit when the amount of change in the detected brightnessexceeds a predetermined threshold, and the luminance control unit maycause the illuminance detection unit to output the illuminance valuebased on the notification.

According to another embodiment of the present invention, there isprovided a program causing a computer to execute the steps of acquiringan illuminance value from an illuminance detection unit to detectbrightness and output an illuminance value corresponding to the detectedbrightness, deriving a luminance set value for controlling a lightemission signal regulating luminance of a light source based on theilluminance value, deriving power consumption information related topower consumption of the light source based on the luminance set value,and displaying the power consumption information on a display screen.

With use of such a program, it is possible to adjust the luminance ofthe light source based on the detected brightness and present a userwith information about the power consumption of the light source,thereby assisting user's luminance adjustment operation.

According to the embodiments of the present invention described above,it is possible to adjust the luminance of a light source based ondetected brightness and present a user with information about the powerconsumption of the light source, thereby assisting user's luminanceadjustment operation.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an explanatory view to describe an example of a method ofderiving a luminance set value in an information processing apparatusaccording to an embodiment of the present invention.

FIG. 2 is an explanatory view to describe significance of presentinginformation about power consumption of a light source in an informationprocessing apparatus according to an embodiment of the presentinvention.

FIG. 3 is an explanatory view showing an example of a means of derivinginformation about power consumption of a light source.

FIG. 4 is a block diagram showing an example of a configuration of aninformation processing apparatus according to an embodiment of thepresent invention.

FIG. 5 is an explanatory view showing an example of a hardwareconfiguration of an information processing apparatus according to anembodiment of the present invention.

FIG. 6 is a flowchart showing an example of processing of an illuminancedetection unit included in an information processing apparatus accordingto an embodiment of the present invention.

FIG. 7 is a flowchart showing a first example of processing of aluminance control unit in an information processing apparatus accordingto an embodiment of the present invention.

FIG. 8 is an explanatory view to describe an example of a method ofsetting an interrupt threshold in an information processing apparatusaccording to an embodiment of the present invention.

FIG. 9 is a flowchart showing a second example of processing of aluminance control unit in an information processing apparatus accordingto an embodiment of the present invention.

FIG. 10 is an explanatory view to describe an example of an applicationof a method of deriving a luminance set value based on a change inluminance level in a luminance control unit of an information processingapparatus according to an embodiment of the present invention.

FIG. 11 is a flowchart showing an example of processing of a displaycontrol unit included in an information processing apparatus accordingto an embodiment of the present invention.

FIG. 12 is an explanatory view showing a first display example ofinformation about power consumption to be displayed on a display screenby a display control unit included in an information processingapparatus according to an embodiment of the present invention.

FIG. 13 is an explanatory view showing a second display example ofinformation about power consumption to be displayed on a display screenby a display control unit included in an information processingapparatus according to an embodiment of the present invention.

FIG. 14 is an explanatory view showing another display example to bedisplayed on a display screen by a display control unit included in aninformation processing apparatus according to an embodiment of thepresent invention.

FIG. 15 is an explanatory view to describe a case where no change occursin luminance of a light source when a change is made to a luminancelevel.

FIG. 16 is an explanatory view showing another display example to bedisplayed on a display screen by a display control unit included in aninformation processing apparatus according to an embodiment of thepresent invention.

FIG. 17 is an explanatory view showing another display example to bedisplayed on a display screen by a display control unit included in aninformation processing apparatus according to an embodiment of thepresent invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Hereinafter, preferred embodiments of the present invention will bedescribed in detail with reference to the appended drawings. Note that,in this specification and the appended drawings, structural elementsthat have substantially the same function and structure are denoted withthe same reference numerals, and repeated explanation of thesestructural elements is omitted.

Although a light source (e.g. a backlight) that constitutes an LCD(Liquid Crystal Display) is described hereinafter as an example of alight source whose luminance is adjusted by an information processingapparatus according to an embodiment of the present invention, thepresent invention is not limited thereto. For example, an informationprocessing apparatus according to an embodiment of the present inventionmay adjust the luminance of a light source that constitutes anon-self-luminous display device having a separate light source, such asa DMD (Digital Micromirror Device).

Hereinafter, the description will be given in the following order.

1. Approach according to an embodiment of the present invention.

2. Information processing apparatus according to an embodiment of thepresent invention.

3. Program according to an embodiment of the present invention.

(Approach According to an Embodiment of the Present Invention)

An information processing apparatus (which is referred to hereinafter asan “information processing apparatus 100”) according to an embodiment ofthe present invention adjusts the luminance of a light source based ondetected brightness. Further, the information processing apparatus 100presents a user with information about the power consumption of thelight source, thereby assisting the user to perform luminance adjustmentoperation. Before describing the configuration of the informationprocessing apparatus 100, an approach for adjustment of the luminanceand presentation of information about the power consumption of the lightsource is described below.

The information processing apparatus 100 adjusts the luminance of alight source based on detected brightness and presents a user withinformation about the power consumption of the light source byperforming “processing of adjusting luminance” and “processing ofpresenting information about power consumption”. The outline of“processing of adjusting luminance” and “processing of presentinginformation about power consumption” in the information processingapparatus 100 is described hereinafter.

[1] Processing of Adjusting Luminance

The information processing apparatus 100 adjusts the luminance of alight source by two luminance adjustment methods: a first luminanceadjustment method based on detected brightness and a second luminanceadjustment method based on user's operation (luminance adjustmentoperation by a user), for example.

The first luminance adjustment method according to an embodiment of thepresent invention is a method that adjusts the luminance of a lightsource by deriving a luminance set value for controlling a lightemission signal that regulates the luminance of the light source basedon an illuminance value according to detected brightness, for example.Thus, the first luminance adjustment method is an automatic luminanceadjustment method without need of user's operation, for example. Amethod of deriving a luminance set value according to an embodiment ofthe present invention is described later.

The second luminance adjustment method according to an embodiment of thepresent invention is a method that adjusts the luminance of a lightsource by performing conditioning to the luminance adjustment by thefirst luminance adjustment method described above. Specifically, theinformation processing apparatus 100 performs conditioning to theluminance adjustment by the first luminance adjustment method by settingone luminance level among a plurality of luminance levels thatrespectively regulate the upper limit and the lower limit of theluminance set value set by the first luminance adjustment method. Theinformation processing apparatus 100 may set the luminance level byproviding a changeover switch for switching the luminance level ordisplaying a switch screen allowing switch setting on a display screen,for example, although not limited thereto. Thus, the second luminanceadjustment method is a manual luminance adjustment method based onuser's operation, for example. In the following, a case where theinformation processing apparatus 100 can set nine luminance levels fromlevel 0 to level 8 (the higher the level is, the higher the luminanceis, for example) is described by way of illustration. The luminancelevel according to an embodiment of the present invention is not limitedto nine levels as a matter of course.

The information processing apparatus 100 may selectively turn off(disable) a function of the luminance adjustment by the first luminanceadjustment method. In such a case, the information processing apparatus100 adjusts the luminance of a light source to be the luminance that isregulated in advance for each luminance level set by the secondluminance adjustment method, for example.

[Method of Deriving a Luminance Set Value]

The information processing apparatus 100 derives the luminance set valueby a function of an illuminance value (which is denoted by “lx” in somecases below) and a luminance level (which is denoted by “LV(x)” in somecases below, where x is a natural number) as represented by thefollowing Expression 1, for example. In Expression 1, “PWM(LV(x), lx)”indicates the luminance set value in a case where a certain luminancelevel is set and a certain illuminance value is detected. Further, inExpression 1, “a(LV(x))” indicates a slope, and “PWM(LV(x), Lmin)”indicates the lower limit of the luminance set value at a certainluminance level. Although Expression 1 is an example in which theluminance set value is represented by a linear function, the method ofderiving a luminance set value according to an embodiment of the presentinvention is not limited thereto. Further, the information processingapparatus 100 sets the lower limit and the upper limit to the luminanceset value when deriving the luminance set value at each luminance levelin Expression 1. This is for the purpose of preventing a light sourcefrom turning out or preventing power consumption of a light source fromincreasing excessively, for example.

PWM(LV(x),lx)=a(LV(x))×lx+PWM(LV(x),Lmin)  Expression 1:

where PWM(LV(x), Lmin)≦PWM(LV(x), lx)≦PWM(LV(x), Lmax)

A method of deriving a luminance set value according to an embodiment ofthe present invention is hereinafter descried more specifically withreference to FIG. 1. FIG. 1 is an explanatory view to describe anexample of a method of deriving a luminance set value in the informationprocessing apparatus 100 according to an embodiment of the presentinvention. FIG. 1 shows five luminance levels: level 0, 2, 4, 6, 8,among nine luminance levels. The other levels (level 1, 3, 5, 7) can bederived in the same manner and thus not shown in FIG. 1.

In FIG. 1, “PWM LV(x)” is a representative value of PWM at eachluminance level, and it corresponds to a value of PWM (which may be setin advance, for example) in the case of not performing the processing[1] (processing of adjusting luminance). Further, in FIG. 1, “Lmin”indicates an illuminance value which corresponds to PWM(LV(x), Lmin),and “Lt” indicates an illuminance value which corresponds to PWM LV(x).In FIG. 1, “Lmax” indicates an illuminance value which corresponds tothe upper limit of the luminance set value at each luminance level. FIG.1 shows an example in which “PWMmax” is set as the upper limit of theluminance set value at an arbitrary luminance level. Because PWMmax isset, even if a detected illuminance value is equal to or lower thanLmax, the information processing apparatus 100 outputs PWMmax as theluminance set value when the luminance set value corresponding to theilluminance value exceeds PWMmax. Although PWMmax may be set to amaximum gradation value (e.g. 255 gradation), for example, it is notlimited thereto. For example, PWMmax may be set to an arbitrary valuethat is smaller than the maximum gradation in order to suppress thepower consumption of a light source.

As shown in FIG. 1, the information processing apparatus 100 derives theluminance set value at each luminance level according to an illuminancevalue based on the line shown in Expression 1, the lower limit at eachluminance level and the upper limit at each luminance level, forexample.

[i] Derivation of a Lower Limit ((PWM(LV(x), Lmin) in Expression 1)

The information processing apparatus 100 derives the lower limit at eachluminance level by using the following Expression 2, for example. InExpression 2, “Min PWM Rate” indicates a rate of the luminance value atLmin in the luminance value at Lt.

PWM(LV(x),Lmin)=(PWM LV(x)−PWM LV0)×(Min PWM Rate)+PWM LV0  Expression2:

[ii] Derivation of a slope (a(LV(x))) in Expression 1

The information processing apparatus 100 derives the slope at eachluminance level by using the following Expression 3, for example, basedon the lower limit at each luminance level and the luminance set valueat Lt, which is PWM LV(x).

a(LV(x))=(PWM LV(x)−PWM(LV(x),Lmin))/(Lt−Lmin)  Expression 3:

The information processing apparatus 100 can derive the luminance setvalue at an arbitrary luminance level and at an arbitrary illuminancevalue by using the above Expressions 1 to 3, the lower limit at eachluminance level and the upper limit at each luminance level, forexample.

The information processing apparatus 100 may derive the luminance setvalue by performing calculation of the above Expressions 1 to 3,comparison of a calculation result with the upper limit and the lowerlimit or the like each time an illuminance value corresponding todetected brightness is transferred from an illuminance sensor, forexample, although not limited thereto. Alternatively, the informationprocessing apparatus 100 may store a look-up table that representsvalues on a line chart at each luminance level as shown in FIG. 1 andcontains luminance values and luminance set values associated inone-to-one correspondence, for example. With use of such a look-uptable, the information processing apparatus 100 can uniquely derive theluminance set value based on the illuminance value.

Further, when a luminance level is changed by user operation or thelike, the information processing apparatus 100 can derive the luminanceset value in the same manner as above based on the latest illuminancevalue and the changed luminance level. A method of deriving a luminanceset value in the case where a luminance level is changed is not limitedthereto. For example, the information processing apparatus 100 may storea parameter for change in luminance level and derive the luminance setvalue according to a change in luminance level based on the changedluminance level and the parameter.

[2] Processing of Presenting Information about Power Consumption (PowerConsumption Information)

Further, the information processing apparatus 100 presents a user withinformation about power consumption of a light source whose luminance isadjusted. The information about power consumption is information fornotifying a user of power consumed in a light source. The informationabout power consumption may be a value of power consumption of a lightsource, a rate in the maximum power consumption of a light source (powerconsumption rate) or the like, though not limited thereto. A method ofpresenting information about power consumption in the informationprocessing apparatus 100 may be displaying information about powerconsumption on a display screen (visual presentation), for example,although not limited thereto. Alternatively, the information processingapparatus 100 may transfer information about power consumption to a userby sound (auditory presentation). In the following, the case where theinformation processing apparatus 100 displays information about powerconsumption on a display screen is described by way of illustration.

[Significance of Presenting a User with Information about PowerConsumption]

The significance that the information processing apparatus 100 presentsa user with information about power consumption is describedhereinafter. FIG. 2 is an explanatory view to describe the significancethat the information processing apparatus 100 according to an embodimentof the present invention presents information about power consumption ofa light source. FIG. 2 shows nine luminance levels that can be perceivedby human eyes as uniform changes and an example of power consumption ofa backlight (light source) at each level. In the following description,a light source is sometimes called a backlight. A light source accordingto an embodiment of the present invention is not limited to a backlightas a matter of course. Although FIG. 2 shows an example in which aluminance level is represented by nine levels, a luminance level is notlimited to nine levels.

As shown in FIG. 2, the brightness which a user actually senses (whichcorresponds to a luminance level) and the power consumption of abacklight at that time do not have a linear relationship. This isbecause human eyes have logarithmic sensitivity characteristics withrespect to outside light. Accordingly, when a user adjusts a luminancelevel based on the brightness of a display screen (e.g. by using thechangeover switch or the like), it is difficult for a user to recognizethe power consumption of the backlight from the brightness perceived bythe eyes. In view of this, the information processing apparatus 100presents a user with information about the power consumption of a lightsource in order to prevent or suppress the occurrence of theabove-described cases (a) and (b), for example. Given the informationabout the power consumption of a light source, a user can recognize howmuch power is consumed in the light source, and it is thereby possibleto set the luminance level more easily according to a purpose.

The information processing apparatus 100 presents information aboutpower consumption of a light source as described above, therebyassisting a user to set a luminance level (the second luminanceadjustment method; luminance adjustment operation by a user).

[Method of Deriving Information about Power Consumption]

A method of deriving information about power consumption in theinformation processing apparatus 100 is described hereinafter.

FIG. 3 is an explanatory view showing an example of a means of derivinginformation about power consumption of a light source. FIG. 3 shows anexample in which a dedicated circuit for deriving information aboutpower consumption (which is referred to hereinafter as “derivationcircuit 12”) is placed between a current regulator 10 and a backlight14, and information about power consumption is derived using thederivation circuit 12.

The current regulator 10 outputs a driving voltage based on a powersupply voltage Vcc and thereby controls a driving current flowing intothe backlight 14. The backlight 14 (light source) emits light withluminance according to the driving current based on the driving voltagetransferred from the current regulator 10. The derivation circuit 12outputs information about power consumption of the backlight 14 based onthe driving voltage output from the current regulator 10.

The derivation circuit 12 includes a current detection resistor R10, asmoothing filter 16 composed of a low-pass filter, a differentialamplifier OP and an A-D converter (Analog-to-Digital converter) 18, forexample. The principle of operation of the derivation circuit 12 shownin FIG. 3 is to measure a current flowing through the current detectionresistor R10 and derive information about power consumption based on ameasured value. Specifically, the derivation circuit 12 shown in FIG. 3derives power consumption by using the following Expression 4 andoutputs power consumption as a digital signal (power consumption data).In Expression 4, “E” indicates a voltage that is input to the A-Dconverter 18, and “R” indicates a resistance value of the currentdetection resistor R10. Further, in Expression 4, “A” indicates a gainof the differential amplifier OP, and “Vcc” indicates a power supplyvoltage.

Power consumption=E/(R×A)×Vcc  Expression 4:

The information processing apparatus 100 can acquire information aboutpower consumption of a light source. by including a dedicated circuitfor deriving information about power consumption as shown in FIG. 3.However, the inclusion of a dedicated circuit as shown in FIG. 3 causesan increase in costs of the information processing apparatus 100. Inlight of this, in order to prevent an increase in costs related toderivation of information about power consumption, the informationprocessing apparatus 100 according to an embodiment of the presentinvention derives information about power consumption by another methodwithout including a dedicated circuit for deriving information aboutpower consumption as shown in FIG. 3.

Specifically, the information processing apparatus 100 derivesinformation about power consumption by the following deriving methods(I) to (III), for example, based on the luminance set value that isderived by the above processing [1]. In the following, the case wherethe information processing apparatus 100 derives a value of powerconsumption and a power consumption rate as information about powerconsumption is described by way of illustration. A method of derivinginformation about power consumption according to an embodiment of thepresent invention is not limited to the following deriving methods (I)to (III).

(I) First Method of Deriving Information about Power Consumption

The information processing apparatus 100 derives a value of powerconsumption and a power consumption rate by using the followingExpression 5 and Expression 6, respectively, for example.

Power consumption rate [%]=(Luminance set value/Maximum luminancevalue)×100  Expression 5:

Value of power consumption [W]=Power at maximum luminance×Powerconsumption rate  Expression 6:

(II) Second Method of Deriving Information about Power Consumption

The information processing apparatus 100 stores a look-up table in whicha luminance set value and a value of power consumption (an example ofinformation about power consumption) are associated in one-to-onecorrespondence, for example. The information processing apparatus 100uniquely derives a value of power consumption based on the luminance setvalue and the look-up table. Then, the information processing apparatus100 derives a power consumption rate by using the derived value of powerconsumption and the following Expression 7.

Power consumption rate [%]=(Power consumption/Power at maximumluminance)×100  Expression 7:

(III) Third Method of Deriving Information about Power Consumption

The information processing apparatus 100 uniquely derives powerconsumption based on a relational expression representing a relationshipbetween a luminance set value and a value of power consumption (e.g. thefollowing Expression 8), for example. Then, the information processingapparatus 100 derives a power consumption rate by using the derivedvalue of power consumption and the above Expression 7. The relationalexpression representing a relationship between a luminance set value anda value of power consumption is not limited to the following Expression8, and it may vary depending on the kind and the number of light sourcesor the like. Thus, the information processing apparatus 100 can uniquelyderive power consumption by an arbitrary relational expressionrepresenting a relationship between a luminance set value and a value ofpower consumption.

Power consumption [W]=a×(Luminance set value)+b  Expression 8:

The information processing apparatus 100 can derive information aboutpower consumption by using the above deriving methods (I) to (III), forexample, based on the luminance set value that is derived by the aboveprocessing [1]. Therefore, it is not necessary for the informationprocessing apparatus 100 to include a dedicated circuit for derivinginformation about power consumption as shown in FIG. 3, therebypreventing an increase in costs of the information processing apparatus100. The information processing apparatus 100 may, of course, include adedicated circuit for deriving information about power consumption asshown in FIG. 3.

The information processing apparatus 100 can present information aboutpower consumption of a light source by deriving information about powerconsumption based on the luminance set value, for example. Thus, theinformation processing apparatus 100 can assist user's luminanceadjustment operation (e.g. operation for the second luminance adjustmentmethod) by presenting a user with information about power consumption ofa light source.

The information processing apparatus 100 performs the above processing[1] (processing of adjusting luminance) and the above processing [2](processing of presenting information about power consumption), forexample. Therefore, the information processing apparatus 100 can adjustthe luminance of a light source based on detected brightness and presenta user with information about the power consumption of the light source,thereby assisting user's luminance adjustment operation.

(Information Processing Apparatus 100 According to an Embodiment of thePresent Invention)

Hereinafter, a configuration of the information processing apparatus 100according to an embodiment of the present invention that achieves theabove-described approach according to an embodiment of the presentinvention is described. FIG. 4 is a block diagram showing an example ofa configuration of the information processing apparatus 100 according toan embodiment of the present invention. Although FIG. 4 shows aconfiguration in which the information processing apparatus 100 includesa light source 116, a display panel 118 forming a display screen onwhich various kinds of information such as information about powerconsumption is displayed or the like, the present invention is notlimited thereto. For example, the information processing apparatus 100may control the luminance of a light source included in anon-self-luminous display device as an external apparatus and displayinformation about power consumption on a display screen of the displaydevice, rather than including the light source 116, the display panel118 or the like.

Referring to FIG. 4, the information processing apparatus 100 includesan illuminance detection unit 102, a control unit 104, a display unit106 and an operation unit 108. The information processing apparatus 100may further include an internal power supply (not shown) that supplies apower supply voltage for driving the respective elements or the like.

Further, the information processing apparatus 100 may include ROM (ReadOnly Memory; not shown), RAM (Random Access Memory; not shown), acommunication unit (not shown), a storage unit (not shown) or the like.In the information processing apparatus 100, the respective elements maybe connected through a bus, which is a data transmission line, forexample.

The ROM stores programs to be used by the control unit 104 and controldata such as calculation parameters. The RAM primarily stores programsto be executed by the control unit 104 or the like. The communicationunit (not shown) has a function of performing wired/wirelesscommunication with an external apparatus via a network (or directly).The network may be a wired network such as LAN (Local Area Network) orWAN (Wide Area Network), a wireless network via a base station such as awireless WAN (WWAN; Wireless Wide Area Network) or a wireless MAN (WMAN;Wireless Metropolitan Area Network), Internet using a communicationprotocol such as TCP/IP (Transmission Control Protocol/InternetProtocol) or the like, for example, although not limited thereto.Further, the communication unit (not shown) may be a communicationantenna and an RF circuit (wireless communication), an IEEE 802.15.1port and a transmitting and receiving circuit (wireless communication),an IEEE 802.11b port and a transmitting and receiving circuit (wirelesscommunication), a LAN terminal and a transmitting and receiving circuit(wired communication) or the like, for example, although not limitedthereto.

The storage unit (not shown) is an information storage means that isincluded in the information processing apparatus 100. With the storageunit included, the information processing apparatus 100 can storevarious data (information) such as OS (Operating System; basic software)and application (application software). The storage unit (not shown) maybe a magnetic recording medium such as hard disk, nonvolatile memorysuch as EEPROM (Electrically Erasable and Programmable Read OnlyMemory), flash memory, MRAM (Magnetoresistive Random Access Memory),FeRAM (Ferroelectric Random Access Memory) or PRAM (Phase-change RandomAccess Memory) or the like, though not limited thereto.

[Exemplary Hardware Configuration of the Information ProcessingApparatus 100]

FIG. 5 is an explanatory view showing an example of a hardwareconfiguration of the information processing apparatus 100 according toan embodiment of the present invention. Referring to FIG. 5, theinformation processing apparatus 100 includes an MPU/chipset 150, ROM152, RAM 154, a recording medium 156, an input/output interface 158, anoperation input device 160, a display device 162, a communicationinterface 164 and an illuminance sensor 166, for example. In theinformation processing apparatus 100, the respective elements areconnected through a bus 168, which is a data transmission line, forexample.

The MPU/chipset 150 is composed of an MPU (Micro Processing Unit), achipset where a plurality of circuits are integrated for implementing acontrol function or the like, and functions as the control unit 104 thatcontrols the information processing apparatus 100 as a whole. TheMPU/chipset 150 may also have a role as a luminance control unit 110 anda display control unit 112, which are described later, in theinformation processing apparatus 100.

The ROM 152 stores programs to be used by the MPU and control data suchas calculation parameters. The RAM 154 primarily stores programs to beexecuted by the MPU or the like.

The recording medium 156 functions as the above-described storage unit(not shown) and stores an application, a look-up table and so on, forexample. The recording medium 156 may be a magnetic recording mediumsuch as hard disk, nonvolatile memory such as flash memory or the like,for example, although not limited thereto.

The input/output interface 158 connects the operation input device 160,the display device 162 or the like, for example. The operation inputdevice 160 functions as the operation unit 108, and the display device162 functions as the display unit 106. The input/output interface 158may be an USB (Universal Serial Bus) terminal, a DVI (Digital VisualInterface) terminal, an HDMI (High-Definition Multimedia Interface)terminal or the like, although not limited thereto. Further, theoperation input device 160 may be placed on the information processingapparatus 100 and connected to the input/output interface 158 inside theinformation processing apparatus 100, for example. The operation inputdevice 160 may be a rotating selector such as a button, a direction keyor a jog dial, a combination of those or the like, for example, thoughnot limited thereto. Further, the display device 162 may be placed onthe information processing apparatus 100 and connected to theinput/output interface 158 inside the information processing apparatus100, for example. The display device 162 may be a non-self-luminousdisplay device such as an LCD (Liquid Crystal Display), though notlimited thereto. Alternatively, the input/output interface 158 may beconnected to an operation input device (e.g. a keyboard or a mouse), adisplay device (e.g. an external display) as an external apparatus ofthe information processing apparatus 100.

The communication interface 164 is a communication means that isincluded in the information processing apparatus 100 and functions as acommunication unit (not shown) that performs wired/wirelesscommunication with an external apparatus via a network (or directly).The communication interface 164 may be a communication antenna and an RFcircuit (wireless communication), an IEEE 802.15.1 port and atransmitting and receiving circuit (wireless communication), an IEEE802.11b port and a transmitting and receiving circuit (wirelesscommunication), a LAN terminal and a transmitting and receiving circuit(wired communication) or the like, for example, although not limitedthereto. The communication interface 164 may have a structure compatiblewith a network, for example.

The illuminance sensor 166 detects brightness in the vicinity of theinformation processing apparatus 100 and selectively outputs anilluminance value according to the detected brightness. A prescribedthreshold is set to the illuminance sensor 166, and when the amount ofchange in the detected brightness exceeds the threshold, the illuminancesensor 166 gives a notification to the MPU (or an application executedby the MPU; which is the same below), for example. Receiving thenotification, the MPU acquires an illuminance value from the illuminancesensor 166. The illuminance sensor 166 can thereby selectively output anilluminance value. Alternatively, the illuminance sensor 166 may outputan illuminance value according to the detected brightness periodicallyor non-periodically.

Communication between the illuminance sensor 166 and the MPU may be madethrough BIOS (Basic Input/Output System; basic software) that isexecuted by the MPU, for example, although not limited thereto.

By the hardware configuration as shown in FIG. 5, for example, theinformation processing apparatus 100 performs the above processing [1](processing of adjusting luminance) and the above processing [2](processing of presenting information about power consumption). Thehardware configuration of the information processing apparatus 100 isnot limited thereto, and a battery (internal power supply) that suppliesa driving power supply to the respective elements or the like may befurther included. The information processing apparatus 100 may have aconfiguration that does not include the display device 162, for example.

Referring again to FIG. 4, the configuration of the informationprocessing apparatus 100 is described hereinafter. The illuminancedetection unit 102 is configured by the illuminance sensor 166, forexample, and detects the brightness in the vicinity of the informationprocessing apparatus 100. Further, the illuminance detection unit 102selectively outputs an illuminance value (or a parameter representing anilluminance value) according to the detected brightness to the controlunit 104 in response to an acquisition request that is transferred fromthe control unit 104 (specifically, the luminance control unit 110,which is described later).

[Example of Processing of the Illuminance Detection Unit 102]

FIG. 6 is a flowchart showing an example of processing of theilluminance detection unit 102 that is included in the informationprocessing apparatus 100 according to an embodiment of the presentinvention.

The illuminance detection unit 102 detects brightness and performsilluminance sampling (S100). Next, the illuminance detection unit 102determines whether the amount of change in illuminance value becomesequal to or larger than (or becomes larger than) a set threshold as aresult of the illuminance sampling in the step S100 (S 102). Thethreshold that is set to the illuminance detection unit 102 is set bythe control unit 104 (specifically, the luminance control unit 110,which is described later), for example. An example of the threshold thatis set to the illuminance detection unit 102 is described later withreference to FIG. 8.

If it is not determined in the step S102 that the amount of change inilluminance value becomes equal to or larger than the set threshold, theilluminance detection unit 102 repeats processing from the step S100.

On the other hand, if it is determined in the step S102 that the amountof change in illuminance value becomes equal to or larger than the setthreshold, the illuminance detection unit 102 transmits an interruptsignal to the control unit 104 (specifically, the luminance control unit110, which is described later) (S 104). Communication between theilluminance detection unit 102 and the control unit 104 is performedthrough BIOS, for example, though not limited thereto. The interruptsignal that is transmitted from the illuminance detection unit 102corresponds to a notification from the illuminance detection unit 102 tothe control unit 104.

After transmitting the interrupt signal in the step S104, theilluminance detection unit 102 determines whether an acquisition requestfor an illuminance value is received (S 106). The acquisition requestfor an illuminance value is transmitted from the control unit 104(specifically, the luminance control unit 110, which is described later)in response to reception of the interrupt signal, for example. Further,although the illuminance detection unit 102 may perform thedetermination of the step S106 based on the received acquisition requestfor an illuminance value, for example, the present invention is notlimited thereto. For example, the illuminance detection unit 102 maydetermine whether the acquisition request for an illuminance value isreceived according to a change in signal level of a signal transferredto a particular signal line.

If it is not determined in the step S106 that the acquisition requestfor an illuminance value is received, the illuminance detection unit 102does not proceed to the next step until it is determined that theacquisition request for an illuminance value is received. If theacquisition request for an illuminance value is not received after alapse of a prescribed time period from the transmission of the interruptsignal in the step 104, the illuminance detection unit 102 may performthe processing of the step S104 again, for example.

On the other hand, if it is determined in the step S106 that theacquisition request for an illuminance value is received, theilluminance detection unit 102 outputs an illuminance value (S108). Theilluminance value that is output in the step S108 is transferred to thecontrol unit 104 (specifically, the luminance control unit 110, which isdescribed later), through BIOS, for example.

The illuminance detection unit 102 can selectively output an illuminancevalue by the processing as shown in FIG. 6, for example. In the casewhere the illuminance detection unit 102 performs the processing shownin FIG. 6, the illuminance detection unit 102 performs the thresholddetermination processing in the step S102, and it is therefore notnecessary to perform the threshold determination processing in thecontrol unit 104 that includes the MPU or the like, for example, in theinformation processing apparatus 100. Generally, power consumption of anilluminance sensor necessary for processing is lower than powerconsumption of an MPU necessary for processing. Thus, by including theilluminance detection unit 102 that performs the processing as shown inFIG. 6, the information processing apparatus 100 can reduce the powerconsumption that is necessary for the processing [1] (processing ofadjusting luminance).

The processing in the illuminance detection unit 102 according to anembodiment of the present invention is not limited to the processingshown in FIG. 6. For example, the illuminance detection unit 102 maytransfer a result of the illuminance sampling in the step S100 to thecontrol unit 104 each time sampling is performed or non-periodically.Further, although not shown in FIG. 6, the illuminance detection unit102 may enter an interrupt state that suspends the illuminance samplingprocessing in the step S100 after outputting the interrupt signal in thestep S104. The interrupt state in the illuminance detection unit 102 isreleased by an interrupt release instruction that is transferred fromthe luminance control unit 110, for example. As a result that theilluminance detection unit 102 enters the interrupt state as describedabove, it is possible to prevent an interrupt signal from beingtransferred during the processing of deriving the luminance set value inthe luminance control unit 110, for example. The information processingapparatus 100 can thereby adjust the luminance of a light source withmore stability, for example.

Referring again to FIG. 4, the configuration of the informationprocessing apparatus 100 is described. The control unit 104 is composedof an MPU, a chipset or the like, for example, and has a function ofcontrolling the information processing apparatus 100 as a whole.Further, the control unit 104 includes the luminance control unit 110and the display control unit 112, and has a role to perform the aboveprocessing [1] (processing of adjusting luminance) and the aboveprocessing [2] (processing of presenting information about powerconsumption).

The luminance control unit 110 derives the luminance set value based onan illuminance value that is output from the illuminance detection unit102 or a switch signal according to operation input or the like in theoperation unit 108, which is described later, for example. The switchsignal is a signal that triggers processing of changing a luminancelevel and indicates a luminance level after change, for example.

[Processing 1 of the Luminance Control Unit 110: Processing of Derivinga Luminance Set Value Based on an Illuminance Value]

FIG. 7 is a flowchart showing a first example of processing of theluminance control unit 110 in the information processing apparatus 100according to an embodiment of the present invention. FIG. 7 shows anexample of processing of deriving a luminance set value based on anilluminance value in the information processing apparatus 100.

The luminance control unit 110 performs initial setting of anilluminance sensor that forms the illuminance detection unit 102 (S200).Then, the luminance control unit 110 sets a threshold for transmittingan interrupt signal to the illuminance sensor (S202).

<Method of Setting an Interrupt Threshold>

FIG. 8 is an explanatory view to describe an example of a method ofsetting an interrupt threshold in the information processing apparatus100 according to an embodiment of the present invention. FIG. 8 shows anexample in which a luminance level is 8. In FIG. 8, P1 indicates thecurrent illuminance and luminance, and P2 indicates the illuminance andluminance after change. A method of setting an interrupt threshold isdescribed hereinafter, taking before and after updating the luminance asan example.

The luminance control unit 110 sets a lower-illuminance threshold Xl1and a higher-illuminance threshold Xu1 with respect to the currentilluminance x1 as the interrupt threshold. The luminance control unit110 sets two thresholds of a lower-illuminance threshold and ahigher-illuminance threshold because the detected brightness can changeto be both darker and brighter depending on a change in the peripheralenvironment of the information processing apparatus 100. Thus, theinterrupt threshold that is set by the luminance control unit 110 is athreshold for determining the amount of change in illuminance value.

The luminance control unit 110 sets a lower-illuminance change amount[%] and a higher-illuminance change amount [%] as thresholds in advance,calculates a lower-illuminance threshold and a higher-illuminancethreshold by using the following Expression 9 and Expression 10,respectively, and causes the illuminance detection unit 102 to set thelower-illuminance threshold and the higher-illuminance threshold, forexample. A method of setting a lower-illuminance threshold and ahigher-illuminance threshold in the information processing apparatus 100is not limited to the above method. Further, although it is typical thatthe illuminance detection unit 102 includes a plurality of sensors withdifferent wavelength sensitivity and an illuminance value is calculatedfrom measured values of those sensors, there is a case where a value ofonly one sensor element can be used for threshold determination. In sucha case, an interrupt threshold may be set to a value of the sensorhaving wavelength sensitivity that is the closest to human sensitivitycharacteristics.

Lower-illuminance threshold after change=Illuminance value afterchange×(Lower-illuminance change amount [%]/100)  Expression 9:

Higher-illuminance threshold after change=Illuminance value afterchange×(Higher-illuminance change amount [%]/100)  Expression 10:

If an illuminance value that is detected by the illuminance detectionunit 102 is larger than (or equal to or larger than) either one of thelower-illuminance threshold Xl1 or the higher-illuminance threshold Xu1,the illuminance detection unit 102 transfers the interrupt signal to theluminance control unit 110. Upon receiving the interrupt signal, theluminance control unit 110 acquires an illuminance value from theilluminance detection unit 102 and derives a luminance set value by themethod of deriving a luminance set value described above. As a resultthat the luminance control unit 110 derives the luminance set value, thecurrent illuminance and luminance change from P1 to P2. Then, theluminance control unit 110 transfers a new lower-illuminance thresholdXl2 to the illuminance detection unit 102, so that a higher-illuminancethreshold Xu2 is set as the interrupt threshold.

The information processing apparatus 100 can set the interrupt thresholdcorresponding to the derived luminance set value by the above-describedmethod, for example. A method of setting an interrupt thresholdaccording to an embodiment of the present invention is not limitedthereto.

Referring again to FIG. 7, an example of processing of deriving aluminance set value based on an illuminance value in the informationprocessing apparatus 100 is described hereinafter. After setting theinterrupt threshold in the step S202, the luminance control unit 110releases the interrupt state of the illuminance sensor of theilluminance detection unit 102 (S204). In the configuration where theilluminance detection unit 102 does not enter the interrupt state, theluminance control unit 110 does not perform the processing in the stepS204.

The luminance control unit 110 determines whether the interrupt signaltransferred from the illuminance detection unit 102 is detected (S206).If it is not determined in the step S206 that the interrupt signal isdetected, the luminance control unit 110 does not proceed to the nextstep until it is determined that the interrupt signal is detected.

On the other hand, if it is determined in the step S206 that theinterrupt signal is detected, the luminance control unit 110 acquires anilluminance value from the illuminance detection unit 102 (S208). Theluminance control unit 110 acquires an illuminance value by transmittingan acquisition request for an illuminance value to the illuminancedetection unit 102, for example.

After acquiring the illuminance value in the step S208, the luminancecontrol unit 110 derives a luminance set value (S210). The luminancecontrol unit 110 may derive the luminance set value based on the setluminance level and the illuminance value by using the method ofderiving a luminance set value described above, for example. Informationof the currently set luminance level for deriving a luminance set valueis stored in the recording medium 156 or the like, and the luminancecontrol unit 110 derives the luminance set value by appropriatelyreading the information of the luminance level from the recording medium156, for example.

After deriving the luminance set value in the step S210, the luminancecontrol unit 110 outputs the derived luminance set value to the displaycontrol unit 112 or a light source control unit 114, which are describedlater (S212). As a result that the luminance control unit 110 transfersthe luminance set value to the display control unit 112, the displaycontrol unit 112 can derive information of power consumptioncorresponding to luminance setting and present a user with theinformation of power consumption. Further, as a result that theluminance control unit 110 transfers the luminance set value to thelight source control unit 114, the light source control unit 114 cancontrol a light source to emit light with the luminance according to theluminance set value.

After outputting the luminance set value in the step S212, the luminancecontrol unit 110 repeats processing from the step S202.

As a result that the luminance control unit 110 performs the processingshown in FIG. 7, for example, it is possible to derive the luminance setvalue each time the amount of change in illuminance value exceeds apredetermined threshold in the illuminance detection unit 102. Further,the luminance set value that is derived by the luminance control unit110 is used for control of the luminance of a light source (which isdescribed later). Therefore, the information processing apparatus 100can adjust the luminance of the light source based on the detectedbrightness.

[Processing 2 of the Luminance Control Unit 110: Processing of Derivinga Luminance Set Value Based on a Change in Luminance Level]

FIG. 9 is a flowchart showing a second example of processing of theluminance control unit 110 in the information processing apparatus 100according to an embodiment of the present invention. FIG. 9 shows anexample of processing of deriving a luminance set value based on achange in luminance level in the information processing apparatus 100.

The luminance control unit 110 determines whether the luminance level ischanged (S300). The luminance control unit 110 may recognize a change inluminance level and a changed luminance level based on a switch signalaccording to operation input by a user using the operation unit 108,operation of a switch screen by a user using the operation unit 108 orthe like, although not limited thereto. The operation input by a usermay be pressing of a changeover button, selection using a rotatingselector such as a jog dial or the like, for example, though not limitedthereto. Further, the switch screen may be a screen where display iscontrolled by the display control unit 112, a screen which isincorporated into the OS or the like, for example, though not limitedthereto.

If it is not determined in the step S300 that the luminance level ischanged, the luminance control unit 110 does not proceed to the nextstep until it is determined that the luminance level is changed.

On the other hand, if it is determined in the step S300 that theluminance level is changed, the luminance control unit 110 derives theluminance set value based on the luminance level after change (S302).The luminance control unit 110 may derive the luminance set value basedon the luminance level according to a switch signal (a changed luminancelevel) and the latest illuminance value by using the method of derivinga luminance set value described above, for example, although not limitedthereto. For example, the luminance control unit 110 may store aparameter for change in luminance level and derive the luminance setvalue according to a change in luminance level based on the luminancelevel according to a switch signal (a changed luminance level) and theparameter. Alternatively, the luminance control unit 110 may derive theluminance set value by updating information of the luminance levelstored in the recording medium 156 to the luminance level according to aswitch signal and reading the updated information of the luminancelevel.

After deriving the luminance set value in the step S302, the luminancecontrol unit 110 outputs the luminance set value in the same manner asthe step S212 in FIG. 7 (S304).

As a result that the luminance control unit 110 performs the processingshown in FIG. 9, for example, it is possible to derive the luminance setvalue corresponding to a changed luminance level each time a luminancelevel changes. Therefore, the information processing apparatus 100 canadjust the luminance of a light source based on a change in luminancelevel.

[Application Processing of Derivation of a Luminance Set Value]

The luminance control unit 110 can derive the luminance set valuecorresponding to a changed luminance level by performing the processingshown in FIG. 9, for example. In the case where a luminance value ischanged largely, when the luminance control unit 110 switches theluminance value before change to the luminance value after change, thereis a possibility that a change in luminance on the display screen isperceived as being too extreme by use's eyes as a result of luminancecontrol based on the derived luminance set value. In light of this, theinformation processing apparatus 100 changes the luminance value to atarget luminance value gradually in multiple steps, for example, inorder to allow a change in luminance when the luminance value changessignificantly to be a more natural change (e.g. a change that causes auser to feel less uncomfortable).

FIG. 10 is an explanatory view to describe an example of an applicationof a method of deriving a luminance set value based on a change inluminance value in the luminance control unit 110 of the informationprocessing apparatus 100 according to an embodiment of the presentinvention. FIG. 10 shows an example of deriving the luminance set valueof the luminance control unit 110 in the case where the luminance valueis changed to be higher.

If the luminance value is changed to be higher or if the illuminancevaries to be higher, the luminance control unit 110 changes theluminance set value in a step-by-step manner to a luminance set valuecorresponding to a target luminance level (which is referred tohereinafter as “target value”). Specifically, the luminance control unit110 increases the luminance level step by step each time a prescribedperiod t elapses by using the following Expression 11, for example. InExpression 11, “PWM Changing Rate” indicates a rate of the upper limitof the amount of change in luminance with respect to the luminancevalue. The upper limit of the amount of change in luminance is set as arate with respect to the luminance value in order to allow a change inluminance when changing the luminance to a target value to be perceiveduniformly. As supplementary explanation, if PWM is incremented one byone, a change is perceived to be faster in a darker region, and a changeis perceived to be slower in a brighter region, and therefore theluminance control unit 110 performs the above processing, for example.

PWM(n+1)=PWM(n)×(100+PWM Changing Rate)  Expression 11:

where PWM(n+1)=target value when PWM(n+1)>target value.

As a result that the luminance control unit 110 increases the luminanceset value that is derived based on the above Expression 11 to a targetvalue in a step-by-step manner, for example, the information processingapparatus 100 can change the luminance of a light source more smoothly.The information processing apparatus 100 can thereby prevent an abruptchange in luminance.

Although the case where the luminance value is changed to be higher orthe illuminance varies to be higher is described above by way ofillustration, the luminance control unit 110 can reduce the luminanceset value to a target value in a step-by-step manner when the luminancevalue is changed to be lower or the illuminance varies to be lower.Specifically, the luminance control unit 110 reduces the derivedluminance set value to a target value step by step by using thefollowing Expression 12, for example.

PWM(n+1)=PWM(n)×(100−PWM Changing Rate)  Expression 12:

where PWM(n+1)=target value when PWM(n+1)<target value.

The luminance control unit 110 can change the luminance of a lightsource more smoothly by using the above Expression 11 and Expression 12,for example. The information processing apparatus 100 can therebyprevent an abrupt change in luminance by the application processing ofderivation of a luminance set value described above.

By performing the above-described processing, for example, the luminancecontrol unit 110 can derive the luminance set value based on theilluminance value that is output from the illuminance detection unit 102and the switch signal according to operation input or the like in theoperation unit 108, for example. The information processing apparatus100 can thereby adjust the luminance of a light source based on thedetected brightness (illuminance value) by including the luminancecontrol unit 110.

The display control unit 112 is composed of an MPU, a chipset, a graphicchip that outputs an image signal to be displayed on a display screen orthe like, for example and has a role to perform the above processing [2](processing of presenting information about power consumption).Specifically, the display control unit 112 derives information aboutpower consumption based on the luminance set value that is derived bythe luminance control unit 110 and presents information about powerconsumption of a light source 116.

<Example of Processing of the Display Control Unit 112>

FIG. 11 is a flowchart showing an example of processing of the displaycontrol unit 112 included in the information processing apparatus 100according to an embodiment of the present invention.

The display control unit 112 determines whether a luminance set value istransferred (S400). If it is not determined in the step S400 that aluminance set value is transferred, the display control unit 112 doesnot proceed to the next step until it is determined that a luminance setvalue is transferred.

If it is determined in the step S400 that a luminance set value istransferred, the display control unit 112 derives information aboutpower consumption of a light source 116 based on the luminance setvalue. The information about power consumption that is derived by thedisplay control unit 112 may be a value of power consumption of thelight source 116, a rate in the maximum power consumption of the lightsource 116 or the like, though not limited thereto

The display control unit 112 can uniquely derive the information aboutpower consumption based on the luminance set value by using theabove-described deriving methods (I) to (III), for example.

After deriving the information about power consumption in the step S402,the display control unit 112 displays the information about powerconsumption on a display screen (S404). A display example of informationabout power consumption to be displayed on a display screen by thedisplay control unit 112 is described hereinafter with reference toFIGS. 12 and 13 where appropriate.

<Display Example of Information about Power Consumption>

(1) First Display Example

FIG. 12 is an explanatory view showing a first display example ofinformation about power consumption to be displayed on a display screenby the display control unit 112 that is included in the informationprocessing apparatus 100 according to an embodiment of the presentinvention. FIG. 12 shows an example of a display screen in the casewhere the information processing apparatus 100 is applied to a notebookPC that includes an LCD.

Referring to V1 of FIG. 12, a power consumption rate (information aboutpower consumption) in a backlight (light source) is represented by ameter that deflects left or right and a numerical value in FIG. 12. Asshown in V1 of FIG. 12, the information about power consumption isvisually presented, so that a user can recognize how much power isconsumed in the light source 116. The information processing apparatus100 can thereby assist a user to set the luminance level according to apurpose.

(2) Second Display Example

FIG. 13 is an explanatory view showing a second display example ofinformation about power consumption to be displayed on a display screenby the display control unit 112 that is included in the informationprocessing apparatus 100 according to an embodiment of the presentinvention.

As shown in V2 of FIG. 13, the display control unit 112 may representthe power consumption rate by a circular meter and a numerical value,not limited to representing the power consumption rate by the meterdeflecting left or right and the numerical value as shown in V1 of FIG.12. As shown in V2 of FIG. 12, the information about power consumptionis visually presented, so that a user can recognize how much power isconsumed in the light source 116.

The display control unit 112 displays the screen as shown in FIGS. 12and 13, for example, on a display screen, thereby visually presentingthe information about power consumption. By including the displaycontrol unit 112, the information processing apparatus 100 can present auser with the information about power consumption of a light source andassist a user to set the luminance level according to a purpose.

A display example of information about power consumption according to anembodiment of the present invention is not limited to the examples shownin FIGS. 12 and 13. For example, the display control unit 112 maypresent a user with a value of power consumption in the same layout asin FIGS. 12 and 13. Further, the display control unit 112 may present auser with information about power consumption by using a meter thatdeflects up or down, or may display both a value of power consumptionand a power consumption rate, for example.

As a result that the display control unit 112 performs the processingshown in FIG. 11, for example, it is possible to present a user withinformation about power consumption of the light source 116. Althoughthe case where the display control unit 112 visually presentsinformation about power consumption is described above, the presentinvention is not limited thereto, and the display control unit 112 mayauditorily present information about power consumption. As a method ofauditorily presenting information about power consumption, the displaycontrol unit 112 may output information about power consumption from anaudio output device composed of a DSP (Digital Signal Processor), anamplifier, a speaker or the like, for example.

<Other Display Examples>

The case where the display control unit 112 displays information aboutpower consumption on a display screen is described in the foregoing.However, the information to be displayed on a display screen by thedisplay control unit 112 is not limited to the information about powerconsumption. As another display example by the display control unit 112,an example of presenting a user with a luminance set value transferredfrom the luminance control unit 110 and a set luminance level isdescribed hereinbelow.

FIG. 14 is an explanatory view showing another display example to bedisplayed on a display screen by the display control unit 112 that isincluded in the information processing apparatus 100 according to anembodiment of the present invention. FIG. 14 shows an example in whichthe display control unit 112 displays a luminance set value and a setluminance level.

As shown in FIG. 14, the currently set luminance level and the currentluminance of the light source are displayed on the display screen, sothat a user can recognize the currently set luminance level and thecurrent luminance of the light source. Although the display control unit112 may represent the luminance of the light source by an actual valueof the luminance set value, the present invention is not limitedthereto. For example, the display control unit 112 may convert the valueof the luminance set value by using the logarithm or the like.

In the case where the currently set luminance level and the currentluminance of the light source are displayed on the display screen asshown in FIG. 14, a case can occur where the luminance of the lightsource 116 does not change even if a user increases the luminance level.FIG. 15 is an explanatory view to describe a case where no change occursin the luminance of the light source 116 when a change is made to theluminance level.

In the case where the upper limit (maximum value) PWMmax of theluminance set value is reached at difference luminance levels as shownin the region A of FIG. 15, the luminance of the light source 116 staysthe upper limit PWMmax and does not change even if a user increases theluminance level. In such a case, user's operation results in nothing.Thus, the display control unit 112 presents a user with a notificationthat luminance does not change even if a luminance level is changed,thereby preventing the occurrence of useless operation by a user asdescribed above.

FIGS. 16 and 17 are explanatory views showing other display examples tobe displayed on a display screen by the display control unit 112 that isincluded in the information processing apparatus 100 according to anembodiment of the present invention. FIGS. 16 and 17 show the screen inthe similar layout to the display screen shown in FIG. 14.

The display control unit 112 clearly indicates that the currentluminance of the light source 116 is a maximum value as shown in FIG.16, for example. By clearly indicating that the current luminance of thelight source 116 is a maximum value as shown in FIG. 16, for example, itis possible to allow a user to recognize that the luminance of the lightsource 116 is already at maximum. The information processing apparatus100 can thereby prevent the occurrence of useless operation by a user asdescribed above. A display example for preventing the occurrence ofuseless operation by a user as described above is not limited to FIG.16. For example, the display control unit 112 may display a messageindicating that the luminance does not increase any more even if theluminance level is set higher. Because the luminance does not changewhen a user performs operation of increasing the luminance level in thestate shown in FIG. 16, display indicating the luminance also does notchange as shown in FIG. 17.

As a result that the display control unit 112 displays the currently setluminance level and the current luminance of the light source on thedisplay screen as shown in FIGS. 14, 16 and 17, it is possible for auser to recognize the currently set luminance level and the currentluminance of the light source.

Further, the display control unit 112 may present a user with both thedisplay screen shown in FIG. 14, 16 or 17 and the display screenpresenting information about power consumption shown in FIG. 12 or 13,for example. In such a case, a user can adjust the luminance level byreferring to information about the current luminance level andinformation about the power consumption of the light source 116, andtherefore the display control unit 112 can provide a higher effect ofassisting a user to set the luminance level according to a purpose.

By including the luminance control unit 110 and the display control unit112, the control unit 104 can perform the above processing [1](processing of adjusting luminance) and the above processing [2](processing of presenting information about power consumption). Althoughthe control unit 104 may implement the processing [1] and the processing[2] described above by software (e.g. a general-purpose MPU or the likeexecutes an application (program) for the processing [1] and [2]), thepresent invention is not limited thereto. For example, the control unit104 may include a dedicated processing circuit (hardware) that performsthe processing [1] and the processing [2] described above and implementthe processing [1] and [2] by using the processing circuit.

The display unit 106 is a display means that is included in theinformation processing apparatus 100. The display unit 106 includes thelight source control unit 114, the light source 116, and a display panel118. Although not shown in FIG. 4, the display unit 106 further includesvarious drivers (scan driver, data driver) for displaying an imagerepresented by an image signal indicating a display screen transferredfrom the display control unit 112 on the display panel 118, for example.

The light source control unit 114 supplies a light emission signal thatcauses the light source 116 to emit light and regulates the luminance ofthe light source 116 to the light source 116 based on the luminance setvalue that is transferred from the luminance control unit 110. The lightsource control unit 114 supplies a driving current based on theluminance set value as the light emission signal to the light source116, so that the light source 116 can emit light at the luminancecorresponding to the luminance set value.

The light source 116 emits light according to the light emission signalthat is supplied from the light source control unit 114. The lightsource 116 may be composed of an LED (Light Emitting Diode) and afluorescent material, for example, although not limited thereto.

The display panel 118 contains a plurality of pixels arranged in amatrix (in an array), for example, and has a role as a display screen onwhich an image (still image/moving image) is displayed. For example, thepanel that displays an image at an SD (Standard Definition) resolutioncontains at least 640×480=307200 (data lines×scan lines) pixels, and ifthe pixels are composed of R, G and B sub-pixels for color display, thepanel contains 640×480×3=921600 (data lines×scan lines×the number ofsub-pixels) sub-pixels. Likewise, the panel that displays a video at anHD (High Definition) resolution contains 1920×1080 pixels, and contains1920×1080×3 sub-pixels for color display.

Further, the display panel 118 includes a pixel electrode (not shown)and a pixel circuit (not shown) for driving the pixel electrode in eachpixel. The display panel 118 also includes a counter electrode(so-called common electrode; not shown) on a surface placed opposite toeach pixel electrode with a given distance therebetween, for example,and a liquid crystal layer is interposed between the surface where thepixels are formed and the surface where the counter electrodes areplaced. The pixel circuit includes a switching element that turns on oroff according to a scan signal that is transferred from the scan lineand applies a data signal corresponding to an image signal that istransferred from the data line to the pixel electrode, for example. As aresult that each pixel circuit selectively applies the data signal tothe pixel electrode, the orientation of liquid crystals between thepixel electrode and the counter electrode changes by an electric fieldaccording to the data signal that is formed between the pixel electrodeto which the data signal is applied and the counter electrode. By suchan operation, a so-called liquid crystal shutter is implemented in thedisplay panel 118. The switching element may be a TFT (Thin FilmTransistor), for example, although not limited thereto.

By the above configuration, the display unit 106 can display informationabout power consumption on the display screen as shown in FIG. 12 or 13,for example, and display other information on the display screen asshown in FIG. 14, for example.

Although a case where the information processing apparatus 100 includesan LCD (Liquid Crystal Display) as the display unit 106 is described inthe foregoing, the configuration of the display unit 106 is not limitedthereto. Further, the information processing apparatus 100 may controlthe luminance of a light source included in a display device as anexternal apparatus and display various kinds of information such asinformation about power consumption on a display screen of the displaydevice, rather than including the display unit 106.

The operation unit 108 is an operating means that enables operation by auser that is included in the information processing apparatus 100. Withthe operation unit 108 included, the information processing apparatus100 can perform processing desired by a user, such as turn on/off of theluminance control according to an embodiment of the present invention.Thus, the operation unit 108 may have a role as a level setting unit forsetting a luminance level. The operation unit 108 may be an operationinput device such as a keyboard or a mouse, a rotating selector such asa button, a direction key or a jog dial, a combination of those or thelike, for example, though not limited thereto.

By the configuration shown in FIG. 4, for example, the informationprocessing apparatus 100 can perform the above processing [1](processing of adjusting luminance) and the above processing [2](processing of presenting information about power consumption).Therefore, the information processing apparatus 100 can adjust theluminance of a light source based on detected brightness and present auser with information about the power consumption of the light source,thereby assisting user's luminance adjustment operation.

As described in the foregoing, the information processing apparatus 100according to an embodiment of the present invention includes theilluminance detection unit 102 and the control unit 104 and performs theprocessing [1] (processing of adjusting luminance) and the processing[2] (processing of presenting information about power consumption)described above. The information processing apparatus 100 derives aluminance set value for controlling a light emission signal thatregulates the luminance of a light source based on an illuminance valueaccording to detected brightness and a set luminance level. Thus, theinformation processing apparatus 100 can adjust the luminance of thelight source based on the detected brightness. Further, the informationprocessing apparatus 100 derives information about power consumptionbased on the derived luminance set value, thereby presenting a user withthe information about power consumption of the light source. Given theinformation about the power consumption of the light source, a user canrecognize how much power is consumed in the light source, a power savingeffect by the set luminance level or the like, and it is therebypossible to set the luminance level more easily according to a purpose.Thus, a user can perform an operation for preventing the occurrence ofthe above-described cases (a) and (b) based on the presented informationabout the power consumption of the light source. Accordingly, bypresenting the information about the power consumption of the lightsource, the information processing apparatus 100 can assist user'sluminance adjustment operation such as setting of a luminance level by auser (second luminance adjustment method). The information processingapparatus 100 can thereby adjust the luminance of the light source basedon detected brightness and present a user with the information about thepower consumption of the light source, thereby assisting user'sluminance adjustment operation.

Further, because the information processing apparatus 100 derives theinformation about the power consumption based on the luminance setvalue, it is possible to derive the information about the powerconsumption without including a dedicated detection circuit as shown inFIG. 3, for example. The information processing apparatus 100 canthereby prevent an increase in hardware costs for implementing the aboveprocessing [1] (processing of adjusting luminance).

Although the information processing apparatus 100 is described in theforegoing as an embodiment of the present invention, the embodiment ofthe present invention is not limited thereto. The embodiment of thepresent invention may be applied to various kinds of equipment includingcomputers such as all-in-one PC and notebook PC including a PC and adisplay device, portable communication apparatus such as cellular phonesand PHS (Personal Handyphome System), video/music playback apparatussuch as WALK MAN (registered trademark), portable game machines such asPlaystation Portable (registered trademark), non-self-luminous displayapparatus such as LCD and so on.

(Program Related to the Information Processing Apparatus According to anEmbodiment of the Present Invention)

With use of a program that causes a computer to function as theinformation processing apparatus 100 according to an embodiment of thepresent invention, it is possible to adjust the luminance of a lightsource based on detected brightness and present a user with informationabout the power consumption of the light source, thereby assistinguser's luminance adjustment operation.

It should be understood by those skilled in the art that variousmodifications, combinations, sub-combinations and alterations may occurdepending on design requirements and other factors insofar as they arewithin the scope of the appended claims or the equivalents thereof.

For example, although the case of providing a program (computer program)that causes a computer to function as the information processingapparatus 100 according to an embodiment of the present invention isdescribed above, the embodiment of the present invention may furtherprovide a storage medium that stores each of the above programs.

The above-described configuration shows an example of an embodiment ofthe present invention, which is intended for inclusion within the scopeof the present invention.

The present application contains subject matter related to thatdisclosed in Japanese Priority Patent Application JP 2008-231273 filedin the Japan Patent Office on Sep. 9, 2008, the entire content of whichis hereby incorporated by reference.

What is claimed is:
 1. An electronic device comprising: circuitryconfigured to detect brightness and output an illuminance valuecorresponding to the detected brightness; derive a luminance set valuefor controlling a light signal setting luminance of a light source basedon the luminance value and one luminance level among a plurality ofluminance levels; derive power consumption information related to powerconsumption and/or a power consumption rate consumed in the light sourcebased on the luminance set value; and control a display to display thepower consumption information.
 2. The electronic device of claim 1,wherein the circuitry is configured to: set one luminance level among aplurality of luminance levels regulating a lower limit and an upperlimit of the luminance set value; and derive the luminance set valuebased on the set luminance level and the illuminance value.
 3. Theelectronic device of claim 2, wherein if the set luminance level ischanged, the circuitry is configured to derive a luminance set valuecorresponding to a luminance level after change from the luminance setvalue corresponding to the luminance level before change in astep-by-step manner.
 4. The electronic device of claim 1, wherein thecircuitry is configured to derive at least one of power consumption anda power consumption rate as the power consumption information.
 5. Theelectronic device of claim 1, further comprising: a light source,wherein the circuitry is configured to transfer a light emission signalcorresponding to the luminance set value to the light source based onthe derived luminance set value.
 6. The electronic device claim 1,wherein the circuitry is configured to: output a notification when anamount of change in the detected brightness exceeds a predeterminedthreshold; and output the illuminance value based on the notification.7. A method performed by an electronic device, the method comprising:detecting brightness and output an illuminance value corresponding tothe detected brightness; deriving a luminance set value for controllinga light signal setting luminance of a light source based on theluminance value and one luminance level among a plurality of luminancelevels; deriving power consumption information related to powerconsumption and/or a power consumption rate consumed in the light sourcebased on the luminance set value; and controlling a display to displaythe power consumption information.
 8. A non-transitory computer-readablemedium including computer-program instructions, which when executed byan electronic device, cause the electronic device to: detect brightnessand output an illuminance value corresponding to the detectedbrightness; derive a luminance set value for controlling a light signalsetting luminance of a light source based on the luminance value and oneluminance level among a plurality of luminance levels; derive powerconsumption information related to power consumption and/or a powerconsumption rate consumed in the light source based on the luminance setvalue; and control a display to display the power consumptioninformation.